Smart Soot Sensor for Particulate Filter OBD 2013-01-1334

In the frame of tighter emission requirements and environmental protection, future standards will soon lead to the use of an OBD soot sensor to monitor DPF leakage. Such a sensor will first be introduced in the US by MY 2015 and then in Europe for Euro 6.2 in 2017. The resistive ceramic sensing technology has been selected by most OEM as the most appropriate. The sensor collects the soot in a time cumulative manner and has an internal heater to clean the ceramic before each measurement sequence. The actual challenge of the hardware is to design a wide band collecting system with a high sensitivity and repeatability circuit processing. Electricfil has overcome major drawbacks of the resistive technology with an innovative sensor tip, with filtration features and a boosting electronic scheme. This sensor integrates internal diagnostic capability at power on and during operation.

But the most challenging task of the smart soot sensor is to be able to diagnose filter leakage what ever the driving condition are, smoother or tighter than the standard NEDC, FTP or WLTC cycles. The goal is to guarantee a robust detection of failure with no more than 1ppm false detection and no more than 100ppm of undetected leakage. In order to accommodate with OEM request and available database, Electricfil and IFPEN have developed two strategies, one assuming that the engine soot cartography is available and a second one without. Both predictive techniques have been simulated and show very good results. Intensive testing are on going to characterize the performances of these strategies on real time driving conditions with several vehicles.

The paper will describe the innovative hardware and software solutions and present the simulated and measured performances.